Pulverizing mill separator, having whizzer and directional vanes



3113724, 1951 J. cRmss 2,561,564

PULVFRIZING ILL SEPRTOR, HAVING 'HIZZER AND DIREcTroNAL vANEs med Aug. 2s, 194e Figfl,

INVENTOR Joe Crites ATTORNEY Patented July 24, 1951 PULVERIZING MILL SEPARATOB, HAVING WHIZZER AND DIRECTIONAL VANES Joe Crites, Evanston, Ill.,'assignor to Combustion Engineering- Superheater, Inc.. a corporation of DE] aware Application August 23, 1948. Serial No. 45,747

1 Claim. l 1 k This invention relates to mills for pulverizing material and particularly to high speed mills for Spaced above the rotating hammers is a fan4 with its suction inlet adjacent the mill casing which creates a iiow of air or gas upwardly through the mill' casing and carries the sutilciently ground material entrained with the air out of `the mill. Between the hammers and the ian and within the mill casing may be a whizzer or whiazers, which comprise a multiplicity of radial arms or blades rotatable about a shaft at very high speeds. The shaft supporting the whizzer hlades may be a continuation of the shaft carrying the hammers. The whizzers act to increase the rotation of the dust laden air leaving the grinding zone and the resulting centrifugal force concentrates the insufficiently ground material adjacent the mill casing whence it returns to the zone for further grinding.

Due to the high rotational speeds of the hammers :and particularly the whizzer, and consequently the high rotational speed of the air at the 1an inlet, it has heen found that the Ian is not effective and that a normal size fan provides an extremely low air ilow which is objectionable.

It is `an object of this invention to provide novel means for overcoming the above objections.

Figure l is a central vertical section through a high speed mill embodying the invention.

Figure 2 is a horizontal section taken on line 2 2 of Figure 1.

Figure 2a is a horizontal partial section also taken on line 2-2 of Figure 1, but showing a modification of the invention other than shown by Figure 2.

The apparatus comprises in general an outer cylindrical mill casing i provided with a liner 2, a i'an chamber 3 in the upper portion of the casing, a top plate I, a base structure supporting the casing and a sub base 6 upon which said plate i rests. Within the casing is a rotary assembly comprising a shaft l mounted for rotation in top andbottombearingetandandcxtending through the axis of the casing. Upon shaft 'I there is mounted grinding element I0, a multiplicity of whizzer blades II and a Ian I2, the latter being located within the fan chamber 3 of the casing i. The shaft extends downwardly below the bearing 9 and is provided with a pulley I3 suitable for a multiple V-belt drive as shown.

Below the fan l2 the mill casing I is provided with an inwardly extending iiange I4 having a central opening I5 through which the air from the mill passes to the fan I2. Within the base 5 there is provided an air inlet I6 and a conduit I1 through which air is admitted into the mill casing I below the grinding element I0. Air enters the mill through said inlet I6, passes upwardly throughl the casing around the grinding element IU, thence upwardly through the whizzers II, thence through the fan intake I5 to the fan I2 to be discharged through an opening of the casing not shown.

.A feeder Il is provided and comprises a. hopper I9 having a tube 2B extending through the wall of the mill casing l and a screw feed 2| whose shaft 22 extends through the hopper I9 :and the bearing 23 to the sprocket Wheel 24 by which shaft 22 is rotated (by driving means not shown). Upon rotation of the screw feed 2| the material to be pulverized is delivered into the casing I just above the grinding element I0,

The grinding element III comprises a multiplicity of spaced apart discs 25 mounted on the shaft I to rotate therewith, the discs 25 having a multiplicity of concentrically spaced holes adjacent their periphery, which holes receive pins 26. A multiplicity of hammers 2l are mounted between said discs and are provided with bearings for rotation about the pins 26. When rotating with mill shaft 'I the hammers are held [by centrifugal force in a radial position with respect to the shaft 1.

In accordance with my invention (and for a purpose presently to become evident), a plate 28 having a hole through which shaft l extends is spaced from the bottom side of the inwardly extending ange Il of the mill casing I; this plate 28 is concentrically placed with respect to the axis of the shaft 1 and to the inlet I5 of the fan I2; and a multiplicity of deflecting vanes 29are mounted between the plate 28 and the ange I5 so that any material laden air passing from the mill to the fan inlet must pass in a generally horizontal direction between the spaced detlector vanes. Obviously these deilector vanes 29 may preferably be curved as shown in Fig. 2, or may be straight radial vanes as shown in F13. 2a.

The complete mill further utilizes whlzzers Il mounted on the shaft 'I between the grinding element I and the fan I2.- Each whizzer Il comprises a central disc or plate 30 which is concentric with and extends normal of the shaft 1 and has a plurality of narrow plates or vanes II mounted upon it which project radially outward toward thewall of the lining 2 of the mill casing I. Cooperating with each whizzer I I is an annular defiector l32 carried by the lining 2 of the casing I. This stationary deilector lcomprises an upwardly and inwardly extending conical shell 33 which overlaps the outer end portions of the blades 3|. The beveled ends of the vanes rotate in close proximity to the conical shell 33.

Any insufllciently ground material will be thrown by the rotating blades 3l radially against the lower conical surface 33 of deectors 32 and thence delivered downwardly into the grinding zone for additional treatment; moreover, any insuiliciently ground material being moved by centrifugal force to the space adjacent the lining 2 of the mill casing I and above the deilectors 32 will accumulate upon the top surface of said deflectors and eventually overflow the inner edge thereof and fall between the blades back into the grinding zone for further treatment.

Due to the high rotational speeds of the ham- ;mers 21 and particularly the whizzers Il (typical :speeds by shaft 1 are about`6000 R. P. M. for an 18 inch diameter mill and about 3500 R. P. M. for

a 35 inch diameter mill), and consequently the 'high rotational speed of the air in the zone between the whizzers II and the fan inlet I5, it has 'been found that the fan I2 isl not effective and :that a normal size fan provides an extremely low :air ow which objectionably interferes with the efllcient operation ofthe mill.

laden air in the zone between the whizzers I I andV the plate 28 is not disturbed so that there is no interference with the eilicient centrifugal classiilcation in said zone of the insufficiently ground material from the sufllciently ground material.

While the preferred embodiment of my invention has been shown and described, it will be understood that changes in construction, combination and arrangement of parts may be made without departing from the spirit and scope oi' the invention as claimed.

What I claim is:

In combination with the casing of a pulverizing mill having an inlet in one end and an outlet in the other end, a fan located within said casing and adjacent said outlet to draw gas into said casing through said inlet and discharge a mixture of gas .and pulverized material from said casing through said outlet, a whizzer separator located concentricallv with respect to said fan on the inlet side thereof and remote therefrom and serving to cause a. rotative vortical motion of said gaseous mixture inside said casing at high speed, and stationary vanes adjacent to the inlet of said fan intermediate that inlet and said whizzer separator and remote from the whizzer to arrest said rotative motion. of said gaseous mixture before entrance thereof into said fan, said vanes being circumferentially spaced with respect to the axis of said fan inlet and being curved with the inner ends adjacent the inlet opening arranged radially thereto and the opposite outer ends arranged substantially tangential to the ilow l direction of the entering gaseous mixture.

JOE CRITES.

REFERENCES CITED UNITED STATES PATENTS Number Name Date Re. 20,543 Crites Nov. 2, 1937 577,319 Pfeiffer Feb. 16, 1897 1,756,253 Lykken Apr. 29, 1930 1,791,100 Lykken Feb. 3, 1931 1,826,406 Sturtevant Oct. 6, 1931 1,963,469 Kuhr June 19, 1934 1,967,236 Fraser July 24, 1934 2,055,485 Fraser Sept. 29, 1936 2,069,640 Beardsley Feb. 2, 1937 2,113,586 Fraser Apr. 12, 1938 2,143,100 Anderson Jan. 10, 1939 2,169,680 Crites Aug. 15, 1939 2,195,618 Crites Apr. 2, 1940 2,280,238 Kanowitz Apr. 21, 1942 2,294,921 Lykken Sept. 8, 1942 2,304,264 Lykken Dec. 8, 1942 FOREIGN PATENTS Number Country Date 309,378 Great Britain May 1, 1930 522,534 Germany Apr. 10, 1931 

